Introduction
Welcome to the Bioequivalence Study Sample Size Calculator, a user-friendly app designed to help researchers, biostatisticians, and professionals in pharmaceutical studies quickly calculate the required sample size for bioequivalence (BE) testing. This app uses the powerTOST package, providing a robust tool to compute the sample size necessary to achieve your desired power for bioequivalence trials. Whether you’re working with a 2×2 crossover design or a parallel study design, this tool offers flexibility with essential parameters such as coefficient of variation (CV), geometric mean ratio (GMR), BE limits, target power, and significance level (alpha). It’s an essential resource for those involved in regulatory and clinical research, offering precise, reliable sample size estimates based on the statistical principles behind bioequivalence testing (i.e. two one-sided tests). Learn more about bioequivalence studies and their role in drug development.
How to Use the App
Enter Key Parameters
- Coefficient of Variation (CV%): CV: Within-subject CV for crossover designs; total variability CV for parallel designs.
- Expected Geometric Mean Ratio (GMR): Specify the ratio between the test (T) and reference (R) product’s geometric means.
- Lower and Upper Bioequivalence Limits: Set the regulatory acceptance range for bioequivalence testing (usually 80% to 125%).
- Target Power: Enter your desired statistical power, typically 80% or higher.
- Significance Level (Alpha%): The probability of rejecting the null hypothesis when it’s true (commonly set at 5%).
- Study Design: Select either a one of the crossover designs, or the parallel design.li>
Calculate Sample Size
After entering the parameters, click the “Calculate Sample Size” button. The estimated sample size gives always the total number of subjects (not subject/sequence in crossovers or subjects/group in parallel designs — like in some other software packages).
Interpretation
Another way to interpret TOST is through confidence intervals (CIs):
- If the entire (1 − 2α) × 100% confidence interval lies within [−Δ, Δ], we conclude equivalence.
- If the confidence interval extends beyond the equivalence range, we fail to establish equivalence.
Conclusion and More Resources
The Bioequivalence Study Sample Size Calculator is a powerful tool that simplifies the process of determining the required sample size for your bioequivalence studies.
If you want to learn more about advanced bioequivalence sample size calculations and explore the full capabilities of R’s powerTOST package, we invite you to follow this great tutorial with downloadable R code written by our collaborator Anil Kumar Ganna. Reach out via a contact form for training or consulting in bioequivalence sample size calculation.
